From cb65d0af5492d917d394e0aab70668764a35dd3d Mon Sep 17 00:00:00 2001
From: "Wladimir J. van der Laan" <laanwj@gmail.com>
Date: Wed, 19 Dec 2018 16:02:26 +0100
Subject: [PATCH] Merge #14993: rpc: Fix data race (UB) in InterruptRPC()
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6c10037f72073eecc674c313580ef50a4f1e1e44 rpc: Fix data race (UB) in InterruptRPC() (practicalswift)

Pull request description:

  Fix data race (UB) in `InterruptRPC()`.

  Before:

  ```
  $ ./configure --with-sanitizers=thread
  $ make
  $ test/functional/test_runner.py feature_shutdown.py
  …
  SUMMARY: ThreadSanitizer: data race rpc/server.cpp:314 in InterruptRPC()
  …
  ALL                 | ✖ Failed  | 2 s (accumulated)
  ```

  After:

  ```
  $ ./configure --with-sanitizers=thread
  $ make
  $ test/functional/test_runner.py feature_shutdown.py
  …
  ALL                 | ✓ Passed  | 3 s (accumulated)
  ```

Tree-SHA512: b139ca1a0480258f8caa7730cabd7783a821d906630f51487750a6b15b7842675ed679747e1ff1bdade77d248807e9d77bae7bb88da54d1df84a179cd9b9b987
---
 src/rpc/server.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/rpc/server.cpp b/src/rpc/server.cpp
index 56b10e25b3ac4..133f578548904 100644
--- a/src/rpc/server.cpp
+++ b/src/rpc/server.cpp
@@ -28,7 +28,7 @@
 #include <memory> // for unique_ptr
 #include <unordered_map>
 
-static bool fRPCRunning = false;
+static std::atomic<bool> g_rpc_running{false};
 static bool fRPCInWarmup = true;
 static std::string rpcWarmupStatus("RPC server started");
 static RecursiveMutex cs_rpcWarmup;
@@ -328,7 +328,7 @@ bool CRPCTable::appendCommand(const std::string& name, const CRPCCommand* pcmd)
 bool StartRPC()
 {
     LogPrint(BCLog::RPC, "Starting RPC\n");
-    fRPCRunning = true;
+    g_rpc_running = true;
     g_rpcSignals.Started();
     return true;
 }
@@ -337,7 +337,7 @@ void InterruptRPC()
 {
     LogPrint(BCLog::RPC, "Interrupting RPC\n");
     // Interrupt e.g. running longpolls
-    fRPCRunning = false;
+    g_rpc_running = false;
 }
 
 void StopRPC()
@@ -350,7 +350,7 @@ void StopRPC()
 
 bool IsRPCRunning()
 {
-    return fRPCRunning;
+    return g_rpc_running;
 }
 
 void SetRPCWarmupStatus(const std::string& newStatus)